I JUST CRACKED UP!!!!!

You can't tear down walls willy nilly. You have to know if it is a support wall. If you don't know how to determine that, then you will need to hire a contractor or other professional to tell you.

It's not just breaking down walls, but you also have to consider the ceiling and the floor. If you're in the market for new flooring in the floor isn't as much of a problem as the ceiling because then you have to get new drywall up there and you want to look like it was original

It also depends on how the house is constructed, ie: wood , steel, concrete.

Are blueprints for all structures kept on file somewhere?

A good contractor in your area could look at the obvious support and carrying support walls and advise! Blueprints are helpful but not always necessary. Sometimes, an exploratory hole in an inconspicuous spot can be made if there are questions that can't easily be answered with a visual inspection and easily patched back up.

Make sure they aren't load-bearing walls! That will create an expense you cannot imagine....

Once you determine that the wall is not load bearing, then you have to consider what might be hidden IN the wall ... duct work ... electrical ... plumbing ....

If any of those things are in the wall and have to be moved/rerouted, then you will add considerable expense to your $20 'sledge hammer' project

All the cautionary notes above should be heeded.
Furthermore, walls provide shear value (i.e. the ability of the structure to withstand lateral stress/movement, as in an earthquake.)
When walls are removed, the structure's ability to withstand earthquake stresses may be diminished.
Depending on the extent of work, the proposed floor plan may need to be forwarded to a structural engineer for analysis. Depending on the engineer's findings, supplemental measures may need to be implemented to supplement/restore shear.
I therefore recommend that you consult with a competent contractor before you start.
Good luck!

Good comments. To me, all of the above can be determined when exploring the conditions at the job site. Exploring the structure and accessories is important. I always go for the function as the #1 priority but being respectful of ones budget has to be taken into consideration. The benefit has to outweigh the expense and if I wouldn't do it if it were my house, then I wouldn't recommend that you do it to yours! This photo shows a kitchen which I had removed a wall where you see the indication of the beam above and it carefully was engineered to make sure it was designed to handle the load!

Your question is vague. If you are asking if its a major part of a line item in the demolition portion of a contractors estimate, "no" its not a big expense to the contractor to remove drywall and studs.

The expense is install of dust containment curtains, temporary support prior to removing the wall, the plumbers and electricians cost to remove and relocate wires, outlets, light switches, drains, water supplies. Not to mention any heating or gas lines.

Once the drywall and studs are in a twisted pile, it take more time to pick up, haul outside to dumpster or transfer station, sweep and shop- vac fine particles.

So, if your asking if drywall removal is something that a homeowner can do, the answer is yes. Its not hard to do